Front loading projection unit

ABSTRACT

An improved projection unit which permits removal of the unit&#39;s lamp from the front, concave portion of the unit&#39;s reflector. A first retention member is used to maintain the lamp in pre-established alignment within the reflector and a second retention member, e.g. resilient clamp, is movably oriented on the reflector&#39;s neck portion to secure the first retention member in a first position and release it in a second.

CROSS REFERENCE TO COPENDING APPLICATIONS

An application entitled "Projection Unit Having Removable RetentionMember" was filed Sept. 1, 1977 and is listed in the Patent andTrademark Office under Ser. No. 829,793 now U.S. Pat. No. 4,156,901,Ser. No. 829,793 is assigned to the same assignee as the presentapplication and defines a projection unit which provides facile removaland replacement of the unit's lamp without requiring replacement of theunit's reflector component.

BACKGROUND OF THE INVENTION

The invention relates to incandescent lamp and glass reflectorcombinations for use in projection systems such as 16 mm. movieprojectors.

In many projection units which include a preformed glass reflector andprojection lamp, e.g. tungsten halogen, therein, the lamp is retained inalignment with the reflector by employing a suitable cement, e.g.sauereisen, within the reflector and about the lamp's sealed end.Examples of such arrangements are shown in U.S. Pat. Nos. 3,314,331(Wiley) and 3,639,750 (Anthonijsz). Use of cement of a similarpermanent-type bonding agent prohibits separation of the lamp andreflector in the event that replacement of either of these components isnecessary. In almost all cases, it is only the incandescent lamp whichfails and needs replacement. The aforementioned permanent bond betweenlamp and glass reflector was believed essential to assure precisealignment between said components and between these members and otherelements (e.g. film gate, projection lens) within the overall system.Alignment between reflector and lamp was usually achieved using aprecisioned instrument whereupon the assembled unit was ready forinsertion within a respective socket-holder arrangement, such as shownin U.S. Pat. No. 3,789,212 (Wagner). This latter positioning is usuallyaccomplished by the projector's operator.

Mandatory replacement of both lamp and glass reflector has thereforeresulted in unnecessary waste of material which in turn has addedappreciably to the overall cost of operating such systems.

The projection unit of Ser. No. 829,793 was designed to eliminate theabove undesired requirement by providing a retention member which isremovable from within the reflector yet also assures positive alignmentof the unit's incandescent lamp with the reflector when said lamp ispositioned therein. The retention member is secured to the lamp's sealedend and may comprise a metallic "can", a preformed component ofinsulative material such as ceramic, or a combination of both.

The present invention represents an improvement to the unit of Ser. No.829,793 by providing means whereby the retention member having thesealed end of the lamp therein may be removed from the front, concavereflecting portion of the glass reflector. The method of removal forthese components in Ser. No. 829,793 is through the rear, neck portionof the reflector. This requirement necessitates provision of arelatively large opening within the neck portion and, as a result, thelamp's total forward output is reduced. Rearward removal of the lamp isalso somewhat difficult due to the limited accessibility of this portionof the unit within the overall system.

It can therefore be seen that a projection unit which permits forwardremoval of the unit's incandescent lamp from the glass reflector wouldconstitute an advancement in the art.

OBJECTS AND SUMMARY OF THE INVENTION

It is therefore a primary object of the present invention to enhance theprojection unit art by providing a projection unit which permits readyseparation of the unit's projection lamp from the glass reflectorthrough the front, concave reflecting portion of the reflector.

In accordance with one aspect of the invention, there is provided animproved projection unit which includes a glass reflector, anincandescent projection lamp, and a retention member which is removablyoriented within the glass reflector and serves to maintain alignment ofthe lamp within the reflector. The improvement to the unit comprisesproviding means whereby the retention member, having the lamp retainedtherein, may be facilely removed from the reflector through the front,concave reflecting portion of said reflector.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded isometric view of a projection unit in accordancewith a preferred embodiment of the invention;

FIG. 2 is a side elevation view, partly in section, of the unit of FIG.1 in the assembled position;

FIG. 3 is an isometric view of the unit of FIG. 2 showing the retainingand release positions of the second retention member of the invention;

FIG. 4 is a partial side elevational view, partly in section, showing analternate embodiment of the invention; and

FIG. 5 is a partial aide elevational view, partly in section,illustrating still another embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

For a better understanding of the present invention together with otherand further objects, advantages and capabilities thereof, reference ismade to the following disclosure and appended claims in connection withthe above-described drawings.

In FIGS. 1-3 there is shown an improved projection unit 10 in accordancewith one embodiment of the invention. As stated, unit 10 is particularlyadapted for use within a projection system such as a 16 mm. movieprojector. Accordingly, projection unit 10 would be located within asuitable socket-holder assembly (not shown) such as described and shownin the aforementioned U.S. Pat. No. 3,789,212. Projection unit 10includes a glass reflector 11 and an incandescent projection lamp 13adapted for being located within the reflector (FIG. 2). A preferredlamp 13 for use with the invention is one of the tungsten-halogenvariety which produces 200 watts at a potential of 24 volts. Lamps ofthis type are known in the art and are typically rated for 50 hours ofoperation. Lamp 13 includes an envelope portion 15 having a tungstenfilament structure 17 (FIG. 2) therein. The lamp further includes apress-sealed end portion 19 having a plurality (e.g. two) of electricalcontact wires 21 extending therefrom. Usually, wires 21 are ofmolybdenum or similar conductive materials.

Reflector 11 includes a concave reflecting portion 23 and a hollow neckportion 25 adjacent thereto. Concave portion 23 is preferably ellipticaland includes a thin dichroic internal layer or coating 27. Accordingly,reflector 11 permits much of the heat generated by lamp 13 to passtherethrough while still directing the lamp's visible output in aforward direction ("A") in FIG. 2.

As earlier stated, alignment between lamp 13 and reflector 11 isextremely critical in order to assure optimum forward output of unit 10.Understandably, alignment is also critical between unit 10 and theremaining elements of the overall projection system, such as theprojector's film gate and projection lens. Such elements are well knownin the prior art and are not illustrated here. To maintain saidalignment between lamp 13 and reflector 11, a first retention member 31is utilized and is secured to sealed end 19 of lamp 13. Member 31preferably assures this securement by positively clamping the glass end,as shown fully in FIG. 2. The function of member 31 is to retain lamp 13in alignment within reflector 11 such that the envelope is orientedwithin concave portion 23 of reflector 11 and the lamp's sealed end 19is located substantially within neck 25. Member 31 defines an opening 32therein in which is located sealed end 19 and extending wires 21 of lamp13. Neck portion 25 also includes an opening 33 therein to accommodatemember 31. Opening 33 is significantly smaller than the respectiveopening in the reflector of Ser. No. 829,793. This represents asubstantial improvement over the unit described in Ser. No. 829,793because a smaller opening understandably in an increase in totalinternal reflective area for concave portion 23 to in turn provide anincrease in total forward (direction "A") light output for unit 10. Inthe embodiment of FIGS. 1-3, it is estimated that an increase of fromabout 10 to about 15 percent in forward output over the earlier unitwill be provided. It is preferred that opening 33 is substantiallyrectangular, as shown, and that first retention member 31 is boxlike inconfiguration and thus readily adaptable for being located with theopening.

As a second improvement, it can be seen in FIG. 2 that a greater amountof glass material is provided at the location of juncture of concaveportion 23 and neck 25, in comparison to the earlier unit. This addedthickness serves to strengthen this portion of the reflector, thusfacilitating handling and shipping of said member.

Lamp 13 is retained such that filament structure 17 lies on the centralaxis 35 of reflector 11 and in the focus of the ellipse of reflector 11.In accordance with one embodiment of the invention, this retainedalignment is provided by using at least one clip member 37 (two areshown in FIG. 2). Clips 37, similar to those in Ser. No. 829,793, eachinclude a domed portion 39 which engages the internal walls 41 of member31. Domed portions 39, being metallic, are of sufficient thickness toassure a minor degree of resilience for clips 37. It is understood,however, that once projection unit 10 has been fully assembled, it isnot possible to readily move (e.g. wobble) lamp 13 within the assembly.In other words, the present arrangement assures a positive degree ofstiffness in order to maintain the required alignment between the lampand reflector components. Portions 39 are preferably affixed (e.g. bywelding) to walls 41. Each clip further includes a clamping segment 43which clamps about end 19 in the manner shown. To facilitate thisretention, end 19 includes a pair of opposing upstanding button portions45 and each segment 43 includes an opening 47 to accommodate arespective button. Clips 37 are preferably oriented on end 19 in theoverlapping positioning arrangement described in Ser. No. 829,793.

A ceramic member 51 is secured within an end portion of opening 32 andcontains therein a pair of contact pins 53. Pins 53, one for each wire21, are rigidly positioned within member 51 and are electrically joinedto wires 21. It is preferred to stake contact pins 53 within member 51.In this case, the pins would be located and one end (57 in FIG. 1)staked. It may also be possible to form ceramic member 51 about thecontact pins.

In the projection unit defined in Ser. No. 829,793, the projection lampand retention member secured thereto were inserted into the unit'sreflector through the reflector's neck portion. The method of insertionof the present invention represents a substantial improvement over thisprocedure by providing a means whereby insertion may be accomplishedthrough concave portion 23. Removal is achieved simply by grasping theenvelope 15 and pulling forward after completion of a minor step at therear portion of the unit. This procedure involves movement of a secondretention member 61 which is adapted for occupying first and secondpositions on neck portion 25 of reflector 11. In the first position(shown in phantom in FIG. 3), member 61 positively retains first member31 within the predetermined alignment in reflector 11. When moved to asecond position (shown in solid in FIG. 3), member 31 is released andpermitted to be removed through concave portion 23.

Second retention member 61 is preferably a resilient clamp which isadapted for open expansion (in direction "E" in FIG. 1) to thus beremovable from neck 25. To accommodate member 61, at least one slot 63is provided in neck 25. Member 61 preferably comprises two opposing"jaw" portions 65, 65' which engage respective, opposing sides of neck25. Accordingly, two slots 63 are provided, one for each jaw. Each slotincludes an indented portion 67 in which one of the jaws slides afterbeing located on neck 25. Understandably, the jaws are prohibited fromsliding off neck 25 by the stepped part 69 of each slot, thusnecessitating the described expansion of member 61 before removalthereof may be achieved. Member 61 is retained from sliding off neck 25in the other direction by the end flange 70 of said member.

Clamp 61 includes a pair of extending, flexible arm members 71, 71' eachof which is adapted for positively engaging a corresponding upstandingtab 73 located on first retention member 31. To accommodate member 31and also facilitate alignment thereof, a corresponding pair of grooves75 are provided within open portion 33 of neck 25, one of said grooves75 adapted for having a respective one of said tabs 73 slidably orientedtherein. It is understood of course that only one such tab is needed tosecure positioning of member 31 and lamp 13 within reflector 11. Two arepreferred, however, to provide positive securement on opposing sides ofthe first member. This securement is further enhanced by the provisionof a pair of upstanding projection members 77 located on each side offirst member 31 which includes one of said tabs 73 thereon. Each member77 positively engages a step portion 79 (FIG. 2) within opening 33 ofneck 25 when first retention member 31 is located therein. As shown inFIG. 1, two projections 77 are provided for each tab 73. Accordingly,four such members are preferred and a corresponding number of stepportions similarly provided. Projections 77 are also offset on firstretention member 31 from tab 73 with regard to central axis 35.Engagement of step portions 79 understandably prevents rearward movementof first member 31 beyond the desired aligned position shown in FIG. 2.Additional projection members 78 (FIG. 1) may be provided on theremaining sides of member 31 to further enhance alignment of said memberwithin reflector 11.

With particular reference to FIG. 3, each arm 71, 71' of clamp 61includes an indentation portion 81 therein which mates with a respectiveupstanding tab 73 when in the first, aligned position. Indentationportion 81 and the end of tab 73 possess similar curvatures tofacilitate said engagement and securement. Removal of first member 31 isachieved by provision of a notched portion 83 within each arm 71, 71'such that tabs 73 may align with and pass thereunder when clamp 31 is inthe second non-retaining position.

In FIG. 4 is shown a projection unit 10' in accordance with an alternateembodiment of the invention. Unit 10' comprises the same reflector 11,incandescent projection lamp 13, and first retention member 31 as theunit of FIGS. 1-3. Unit 10' differs from the previous example by theomission of clip members 37. Instead, the sealed end portion 19 of lamp13 is rigidly secured within opening 32 of member 31 by a suitableceramic cement 71 (e.g. sauereisen). Extending wires 21 are also locatedwithin cement 71 and are electrically connected directly to pins 53. Aceramic insulative member 51 is also used.

In the embodiment of FIG. 5, unit 10 utilizes an insulative, e.g.ceramic, first retention member 31' which includes upstanding portions77' thereon which correspond and function in a similar manner toprojection members 77 shown in FIGS. 1-4. Member 31' also includesupstanding portions 73' which correspond and function similarly to tabs73 in the embodiments of FIGS. 1-4. Portions 73' and 77' align with andare oriented in respective grooves, etc. provided within opening 33'similarly to those in the aforedescribed embodiments. A suitable ceramiccement 71' is used to secure end 19 of lamp 13 in the requiredalignment. The extending wires 21 of lamp 13 are directly joined to pins53.

Removal of the above first retention member 31 and lamp 13 securedtherein is accomplished by a simple procedure wherein the unit'soperator slidably moves clamp 61 to the described release positionwhereupon the operator can grasp the lamp's envelope portion 15 andeffect forward removal. No twisting, rotation, or similar motion isrequired.

Thus there has been shown and described an improved projection unitwhich permits disassembly of the unit so that a defective lamp can bereadily removed and replaced through the front of the unit's reflector.The invention assures that the critical alignment between lamp andreflector will be maintained despite continuous lamp insertion andremoval.

While there have been shown and described what are at present consideredthe preferred embodiments of the invention, it will be obvious to thoseskilled in the art that various changes and modifications may be madetherein without departing from the scope of the invention as defined bythe appended claims.

What is claimed is:
 1. In a projection unit including a glass reflectorhaving a front concave reflecting portion and a neck portion adjacentthereto, an incandescent lamp including an envelope portion and a sealedend adjacent said envelope portion, and a first retention memberremovably oriented within said neck portion of said glass reflector forengaging and retaining said sealed end of said lamp therein to maintainsaid lamp in established alignment within said glass reflector wherebysaid envelope portion of said lamp will be located within said frontconcave portion of said reflector and said sealed end of said lamp willbe located within said neck portion, the improvement wherein said firstretention member having said sealed end of said lamp therein isremovable through said front concave reflecting portion of saidreflector.
 2. The improvement according to claim 1 including a secondretention member adapted for occupying first and second positions onsaid neck portion of said reflector, said second retention memberretaining said first retention member within said aligned positionwithin said reflector during said first position and permitting saidremoval of said first retention member and said lamp through saidconcave reflecting portion during said second position.
 3. Theimprovement according to claim 2 wherein said first retention memberincludes at least one upstanding tab thereon, said second retentionmember engaging said tab to effect said retaining of said firstretention member within said reflector during said first position. 4.The improvement according to claim 3 wherein said neck portion of saidreflector includes at least one groove therein, said upstanding tabaligning with said groove during orientation of said first retentionmember within said neck portion of said reflector.
 5. The improvementaccording to claim 3 wherein said neck portion of said reflectorincludes at least two stop portions therein and said first retentionmember further includes at least two upstanding projections locatedthereon in an opposing relationship to said upstanding tab, each of saidprojections aligning with and engaging a respective one of said stopportions when said first retention member is retained by said secondretention member during said first position.
 6. The improvementaccording to claim 3 wherein said second retention member includes atleast one arm member, said arm member having an indentation therein foraligning with said upstanding tab on said first retention member duringsaid first position.
 7. The improvement according to claim 6 whereinsaid arm member includes a notched portion therein for aligning withsaid upstanding tab during said second position to permit said removalof said first retention member.
 8. The improvement according to claim 6wherein the number of said upstanding tabs is two and the number of saidarm members of said second retention member is two, each of said armmembers adapted for aligning with a respective one of said tabs.
 9. Theimprovement according to claim 2 wherein said second retention membercomprises a resilient clamp removably positioned on said neck portion ofsaid reflector.
 10. The improvement according to claim 9 wherein saidneck portion includes at least one slot in the external surface thereof,said resilient clamp movably oriented within said slot during saidoccupancy of said first and second positions.
 11. The improvementaccording to claim 1 wherein said neck portion of said reflectorincludes a rectangular opening therein, said first retention member ofsubstantially boxlike configuration and adapted for being positionedwithin said rectangular opening.